Such object identification devices have been widely used in mobile object control apparatuses, information providing apparatuses and the like. The mobile object control apparatuses perform mobile control on mobile objects such as vehicles, vessels, aircraft and the like. The information providing apparatuses provide valuable information for drivers of the mobile objects. More specifically, for example, there is a known object identification device that is used in a driver assistance system providing AAC (Adaptive Cruise Control) to reduce a driving load for a vehicle driver. In such a vehicle driving assistance system, it becomes necessary to separately recognize (identify) objects including obstacles surrounding the vehicle, leading vehicles, traffic lanes and the like to realize various functions. The various functions include an automatic braking function and an alarming function for the vehicle to avoid a collision with obstacles or the like or to reduce impact due to the collision. The various functions also include a vehicle speed control function to maintain an inter-vehicle distance from a leading vehicle constant and a function to assist the driving vehicle to avoid departing from the running lane where the vehicle is running. To that end, there have been proposed various object identification devices in the past.
Patent Document 1 discloses an object identification device that identifies traffic lanes (objects) to determine a relative displacement between the driving vehicle and the traffic lanes (white lines) by detecting lines in an image obtained by imaging a road image (imaged image). The traffic lanes define the running lane for the vehicle. This object identification device may resolve a problem that puddles are falsely identified as traffic lanes (white lines). The misidetification is caused by a fact that when there are puddles on a road due to rainy weather, sunlight and the like are specular reflected on the puddles and imaged as image data having a similar brightness to that of the traffic lanes (white lines) on the road. Specifically, before a white-line identification process is performed, a region of the puddles is removed from the road image and the white lines are recognized from the remaining scattered-light component. As a method of removing only the specular reflection component, features are used such that a horizontal polarization component of the specular reflection light becomes substantially 0 degrees in Brewster's angle and that the scattered-light component includes a vertical polarization component amount substantially the same as a horizontal polarization component amount. Namely, a difference value between the vertical polarization component and the horizontal polarization component in the imaged road image is calculated. Then, the specular reflection component is calculated by multiplying the difference value by a correction coefficient to remove the specular reflection component in accordance with an incident angle. The specular reflection component is included in the horizontal polarization component. Then, by subtracting the calculated specular reflection component from the horizontal polarization component, an image of the scattered-light component is obtained in which only the specular reflection component is removed from the road image.
Patent Document 1: Japanese Laid-Open Patent Application No. 11-175702.